Process for the production of 3-amino-azacycloheptan-2-one

ABSTRACT

A process is given for the production of 3-amino-azacycloheptan2-one which comprises reducing 1-formyl-3-nitroazacycloheptan-2on with hydrogen under pressure in the presence of ammonia. It is thus possible to obtain 3-amino-azacycloheptan-2-one ( Alpha amino- Epsilon -caprolactam) by a technically simple process.

Foitl et al.

[54] PROCESS FOR THE PRODUCTION OF 3-AMINO-AZACYCLOHEPTAN-2-ONE [72] Inventors: Verena R. Foitl, 58 Nonnenweg,

Basel; Walter Traber, 6 Kappeligasse, Riehen, both of Switzerland [73] Assignee: Ciba-Geigy Corporation, Ardsley, 22 Filed: fill 1124,1970

[21] Appl. No.: 49,559

52 U.S.Cl. .'.260/239.3R 51 Int. Cl. ..c07d 41/06 58 FieldofSearch.., ..-.260/239.3R [56] References Cited -UNITED STATES PATENTS 3,048,580 8/1962 Ottenheym ez a1;.2 0/239.3R

Ottenheym et al..260/239.3 R

Foitl et ..260/239.3 R

Primary Examinerl-lenry R. Jiles Assistant Examiner-Robert T. Bond AttorneyKarl F. Jorda and Frederick H, Rabin 57 ABSTRACT v A process is given for the production of 3-amino-azacycloheptan-Z-one which comprises reducing 1-formyl-3-nitr0azacycloheptan-2-on with hydrogen under pressure in the presence of ammonia. It is thus possi- 4 Claims, No Drawings Y '1 PROCESS FOR THE PRODUCTION OF 3-AMINO- AZACYCLOHEP'IAN-Z-ONE The present invention concerns a new process for the production of 3 -amin'o-azacycloheptan-2 one a amino-e-capro-lactam).

There are a numberof methods knownfor the production of 3-amino azacycloheptan-2-one -(aamino-'e-caprolactam). Themostsimple process known previously was the reduction of 3-nitroazacycloheptan- 2-one (anitro-e-caprolacta'rn) with hydrogen in the presence of a catalyst to the corresponding amine compound (cf. Swiss Pat. No. 375,720). The 3-nitro-azacycloheptan Z-one needed as starting material for this process was obtained from 2-chloro-azacyclo-2,3-heptene by a process'which involved several steps and was thus complicated (cf. British Pat. Nos. 901,169; 867,268; and 867,269). Furthermore it is known that in certaina-halogenocapronic acids the a-halogen atom can be replaced by an amino group by reaction with ammonia. This reaction was applied to a-halogen-ecaprolactam, the desired amino compound, as the hydrochloride, as well as other reaction products being obtained (cf. U.S. Pat. No. 2,876,218).

It has'now been found that 3-amino-azacycloheptan- 2-one is obtained in good purity and good yields by reducing j1-formyl-3-nitro azacycloheptamZ-one with hydrogen under pressure at temperatures between 50 and 150C in the'presence of ammonia and a solvent. Suitable solvents which can be used are those which are inert towards the reaction-components and in which the 3-amino-azacycloheptan-2-one to be produced is readily soluble.v The ready-solubility of the reaction product in the solvent makes it easier to isolate. In particular, solvents which are miscible with water are used. In this way, the liquid phase remains homogeneous during thereduction. Preferred solvents are lower alkanols such as ethanol, methanol, isopropanol as well as mixtures of such alkanols with water. g g

The reduction of the nitro group can be performed with nascent hydrogen or also with molecular hydrogen. It is preferable to perform the reduction with molecular hydrogen in the presence of a catalyst, for example in the presence of Raney-nickel. R'aney-. cobalt, platinum, palladium and other suitablemetals and metallic compounds.

In the process according to the invention, besides the reduction of the nitro group, the formyl group is split off. The formyl group is taken up by ammonia to form formamide or ammonium formiate. It is preferable to employ the ammonia as a gas, since formamide can be easily removed by destillation from the reaction mixture. When concentrated aqueous ammonia solution is used, the formiate is obtained which is difficult to separate. In order to prevent as much as possible the formation of ammonium forrniate, it isadvisable to perform the reaction in an absolute or practically absolute solvent.

In practice, the procedure is as follows: l-formyl-3- nitroazacycloheptan-2-one, ethanol and Raney-nickel are added to a stainless steel autoclave, and ammonia gas is introduced. Then hydrogen gas is introduced into the autoclave in such a manner that the pressure is at least 20 atmospheres. The pressure may vary greatly and may even be increased to 200 to 300 atmospheres. Correspondingly, the reaction temperatures are in a range of from 50-150C. At temperatures higher than that, the r'eaction does not follow the desired course. In

, particular, a .temperaturerange of 50--120.C is used,

preferably in the vicinity of 100C.

The l-forrnyl-3-nitro-azacycloheptan-2 -one serving agent basedfon an N-disubstituted formamide and a halogenating agent and afterwards nitrating the, complex compound obtained as intermediate. By this process which is a one-step process, the starting materi al is obtained in good yields of good purity.

The reduction process according to the invention has, compared with previously known processes, the great advantage of 1 employing as starting material a compound which is easy to produce-Since the formyl group can be easily cleaved, the reduction (hydrogenation) and the cleavage can beperformed in one operation. Accordingly it is now possible to obtain 3-arninoazacycloheptan-2-one (a-amino-e-caprolactam) by' technically simple reactions.

The following example illustrates the process according to the invention. The temperatures are given in degrees centigrade.

.EXAMPLE' removed from the filtrate bydistillation in vacuum. The

residue is then fractionated, formamide distilling first at 45-49/0.04 Torr and then the 3-amino-azacycloheptan-2 one (a-amino-e-caprolactam) at 108'-l09/0.04 Torr. The yield is 26 g, percent of the theory. -When the Raney-nickel is replaced by palladium on charcoal as catalyst, 27 g of the desired amine are obtained.

Production of the starting material: 70 g of phosgene are introduced at 10 to 15, to 51.2 g of dimethylformamide and 30 ml of chloroform. Then the mixture is treated dropwise at 10 to 20 with a solution of 33.9 g of cyclohexanone oxime in ml of chloroform, kept for 12 hours at room temperature and then heated for 2 hours at 50 to 60. The solvent is then removed by distillation in vacuum and the residue is added dropwise at 0 to 10, to a nitrating mixture obtained from 60 ml of concentrated nitric acid and 300 ml of concentrated sulfuric acid. After completion of the addition, the nitrating mixture is poured immediately into ice water, precipitating the nitro compound, The precipitate is separated and washed neutral with water. The resulting I-formyl-S-nitro-azacycloheptan-Z-one, recrystallized from ethanol, has a melting point of l20-l22. The yield is 28.5 g, 51.3 percent of the theory.

What we claim is:

1. A process for the production of B-aminoazacycloheptan-Z-one comprising reducing l-formyl-3- nitroazacycloheptan-2-one with hydrogen at a pressure of from 20 to 200 atmospheres and at a temperature reduction is performed in the presence of a catalyst selected from the group consisting of Raney nickel, palladium, Raney cobalt and platinum.

4. A process according to claim 1, in which the reduction is performed at a pressure of from 20 to 200 atmospheres. 

2. A process according to claim 1, in which the solvent is selected from the group consisting of methanol, ethanol, isopropanol and mixtures thereof.
 3. A process according to claim 1, in which the reduction is performed in the presence of a catalyst selected from the group consisting of Raney nickel, palladium, Raney cobalt and platinum.
 4. A process according to claim 1, in which the reduction is performed at a pressure of from 20 to 200 atmospheres. 